The principal steps in the processing of color photographic materials are a color-development step followed by a desilvering step. In the color-development step, the exposed silver halide is reduced with a color-developing agent to form silver, while the oxidized color-developing agent is reacted with a coupler to form color images. In the desilvering step, the silver formed in the color-development step is oxidized with an oxidizing agent (which is generally called a fixing agent). After the desilvering step, only color images are formed in the color photographic materials.
The desilvering step may be carried out by the use of both a bleaching bath containing a bleaching agent and a fixation bath containing a fixing agent. Alternatively, the step may be carried out by the use of a bleaching-fixation bath containing both a bleaching agent and a fixing agent. Also, desilvering may be accomplished by the use of both a bleaching bath and a bleaching-fixation bath.
Regarding the use of only a bleaching-fixation bath, a method is known where two or more bleaching-fixation baths are provided and a replenisher is fed to the final bath. The overflow solution from the final bath is introduced into the previous bath in order to create a countercurrent system thereby reducing the amount of the replenisher which is used. For example, Japanese Patent Application (OPI) No. 11131/74 (corresponding to OLS-2217570) describes a method for processing photographic materials with two or more continuous bleaching-fixation baths where a recovered solution from the bleaching-fixation bath is replenished in a countercurrent system. (The term "OPI" as used herein means an "unexamined and published application".) Although the amount of waste from the bleaching-fixation solution may be reduced by this method, the desilvering had been found to be insufficient especially when color photographic materials with high iodine content are processed. This is because when photographic materials having high iodine content are processed, the replenisher which is recovered has a higher halogen ion concentration than a standard replenisher. In Japanese Patent Application (OPI) No. 105148/83 a method is described for improving the desilvering efficiency of photographic materials. In this method at least two bleaching-fixation baths are provided and the fixing agent component is primarily replenished in the bleaching-fixation bath positioned nearer to the color-development bath and the bleaching agent component is primarily replenished to the bleaching-fixation bath positioned nearer to the rinsing bath. This process is also carried out in a countercurrent system. In this method, however, since two or more types of replenishers are fed to two or more processing tanks, the operation is complicated and troublesome. Furthermore, desilvering is not always adequate.
The object of the present invention, therefore, is to provide a method for the bleaching-fixation processing of silver halide color photographic materials wherein rapid and sufficient desilvering is achieved while requiring only a small amount of replenisher and maintaining simplicity in operation.
The present inventors have found that when photographic materials are processed in a countercurrent system wherein at least two bleaching-fixation baths are used and a replenisher is fed into the final bath and the overflow solution is introduced into the previous bath, the first bath or the bleaching-fixation bath which is nearest to the color-development bath becomes less active because of the accumulation of color-developer, silver and iodide ion. Consequently, when photographic materials are processed in such a less active bath for a long period of time, not only is the time required desilvering longer but also desilvering is insufficient. The present invention, therefore, is based upon this discovery.